u/Aggravating_Pin_6116

My nitrogen cycle has been going for about a month. My ammonia levels drop from 2ppm to zero in about 24 hours. I have been using seed and a sponge filter I got from the store. The problem I’m having is my nitrites absurdly spiked. Is that normal? This reading is the day after I did a 75% water change. I know it may affect the nitrogen cycle but the bacteria should be mostly on surfaces and filters. Absolutely had to with the spike. Is this just a waiting game at this point? And should I be feeding ammonia in there as well while I wait for the nitrite bacteria to keep the ammonia colony healthy?

I’m brand new. Very brand new. But I’ve always wanted to start this hobby. I bought fancy guppies to start. After only a few hours one floated down. Fought back to the top. Floated down again. Then unfortunately didn’t make it. I’m worried there may not be enough oxygen cause he kept fighting back to the top. The rest seem to be fine but they like hanging by the heater too. I ordered a thermometer but the heater I have says it should be good at 78 and the lights green. I don’t want to lose anymore. What am I doing wrong?